This invention relates to a multi-mode reproducing apparatus preferably of the electrostatographic type. The apparatus includes means for copying documents selectively at a plurality of magnifications.
A variety of electrostatographic reproducing machines are commercially employed which have different modes of operation. One type of machine utilizes a moving original exposure system wherein an original document is moved past a fixed slit optical system for projecting an image onto a moving photoconductive surface. These machines include a means for changing the magnification of the projected image and the speed of the moving original to provide reduction copies. Exemplary of patents in this area are U.S. Pat. Nos. 3,076,392 to Cerasani et al., and 3,649,114 to Vlach et al.
Other machines have been adapted to copy stationary original documents at a variety of magnifications or reductions through the use of a scanning optical system with different scanning speeds and conjugate changing systems. Exemplary of patents in this area are U.S. Pat. Nos. 3,476,478 to Rees, Jr.; 3,542,467 to Furgeson; U.S. Pat. Nos. 3,614,222 to Post; and 3,837,743 to Amemiya.
Another type of variable magnification copier, in which full frame flash exposure is made of a stationary original document, is show, for example, in U.S. Pat. No. 3,778,147 to E. G. Reedhil et al. It discloses delaying the application of the flash energizing pulse in response to the selected magnification ratio.
The aforenoted machines are adapted to provide one or more modes of copying having different magnifications. Other forms of multi-mode copiers are available commercially. For example, in the Xerox 3100 LDC machine an optical system is provided which enables the machine to copy from a stationary original in a first scanning mode or from a moving original in a second fixed optical mode. This latter mode is particularly adapted for copying documents larger than the conventional viewing platen size. U.S. Pat. No. 3,900,258 to Hoppner et al [1] is illustrative of a machine similar in many respects to the 3100 LDC machine.
Reproducing apparatuses including the capability of making copies from both moving and stationary originals are also described in U.S. Pat. No. 3,833,296 to Vola, and in IBM Technical Disclosure Bulletin, Vol. 12, No. 1, at page 173, June 1969.
In U.S. application Ser. No. 549,684, to Bar-on. and U.S. application Ser. No. 598,612 to Hughes, there are disclosed reproducing machines wherein belt type document feeders are utilized for advancing documents over a platen and past a fixed scanning optical system for providing moving original exposure. In the latter application a moving original exposure mode for reduction copying may be employed.
It has been found desirable, to provide a multimode reproducing apparatus having various unique features of the 3100 LDC machine, including its extremely compact size, but also having the capability of reduction copying.
One approach to such a machine is described in U.S. application Ser. No. 588,971 to Hoppner et al. [2]. In that application a multimode reproducing apparatus is provided including both moving and stationary original exposure modes, with at least two modes of moving original exposures at differing copy image magnifications.
In the apparatus of the Hoppner et al. [2] application, only two modes of moving original exposure are shown although additional modes could be provided. One at a nominal magnification wherein the add mirror is positioned out of the optical path and one at a reduced magnification wherein the add mirror is positioned in the optical path. If it is desired to provide multiple reduction modes, then it would be necessary not only to translate the lens to a still different position, but also to adjust the position of the add mirror to again change the appropriate conjugate.
In the Xerox 3100 LDC machine, in the moving original mode of operation, the copying cycle is initiated by the document lead edge intercepting a switch in the document feeder. After the document has actuated the switch, the machine programmer carries out the copying cycle in an appropriately timed sequence. The switch is located upstream of the exposure or viewing position and, therefore, exposure takes place a pre-determined time interval following actuation of the switch.
When performing reduction copying using moving original exposure as in the Hoppner et al. [2], the document is advanced at a more rapid rate and, therefore, it will reach the exposure in a shorter time after actuation of the switch than a document in a 1:1 mode of copying. This will result in a mis-registration between the document and the copy sheet.
In U.S. application Ser. No. 627,432 to Bierworth et al filed of even data herewith, there is described a reproducing machine having a plurality of modes of variable magnification copying by moving original exposure. In that machine, as with the machines noted above, the document is advanced at a variety of speeds proportional to the magnification of the resulting copy image. One feature of that application is the provision of different viewing positions in correspondence to the different projected image magnifications. The use of different viewing positions as well as different document advancing speeds further complicates the problem of obtaining proper registration between the document and the copy sheet when the copying cycle is programmed from the actuation of the document lead edge switch.
Various prior art approaches have been utilized in copying machines for providing copies with a variety of projected image magnifications as noted above. The problem of maintaining registration between the document and the copy sheet for different document advancement rates corresponding to different magnifications has been addressed by the prior art in a variety of ways as, for example, those illustrated in U.S. Pat. Nos. 3,556,655 to Lux et al, and 3,639,057 to Thomas et al. In the Lux et al patent for reduction copying wherein the document is advanced faster than the copy sheet an arrangement is provided whereby the original is momentarily held while the copy sheet advances to center the reduced image on the copy sheet. A time delay relay is utilized to stagger the movement of the original and the copy sheet through the machine so that the copy produced on the copy sheet is centered.